The time of food intake synchronize simultaneously and in parallel way almost all the peripheral metabolic clock genes including those expressed and in peripheral blood cells (PBC) i.e. leucocytes, monocytes; allowing to explore the oscillation of the metabolic clock gene expression of the whole body by assessing its expression in the PBC. Impaired oscillation of the metabolic clock gene mRNA expression was found in diabetic animal models and in patients with type 2 diabetes and were inversely correlated with HbA1c.